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These cases are illustrative of the mode of onset of plague. Many others presented the same train of symptoms previous to the development of the typical and well recognised signs of plague. From these and other cases it is evident that diarrhœa and vomiting are among the early symptoms of plaque. They may be present alone and the individual affected able to go about his daily duties. Sometimes they are accompanied by headache and a feeling of sleepiness but these may be absent.
Again, during this initial stage, there may be no elevation of the body temper- ature. The reports on the microscopical examination of the dejecta say that nothing abnormal was found. Hoards of various micro-organisms were probably present, but the diagnosis of the presence of the plague bacillus in such a medium would be quite impossible. The diagnosis of plague was made absolute by the microscopical examination of the blood. The thick film method of blood examin- ation advocated by Ross for malaria was applied by Dr. BELL to cases of plague. The results were satisfactory and in the majority of cases of a convincing nature.
With a patient complaining of indefinite symptoms, as headache, diarrhoea and vomiting and the finding of oval shaped and bipolar bacteria which decolour- ised by GRAM's method in the thick blood film, during an epidemic of plague in the Colony, the diagnosis or at least provisional diagnosis could only be that of plague.
The presence of the B. pestis in the blood stream of patients suffering from plague is recognised. It is denied, however, that these bacilli are present in the blood during all the stages of the disease. The most modern views on the question are that in the bubonic variety of the disease, plague bacilli are found in the blood only just before death. That is to say the disease becomes septicæmic during the agonal period and numbers of B. pestis appear in the blood. Some observers go so far as to assert that there exists no such thing as septicemic plague. Again in the pneumonic variety of the disease, the same views are held, namely, the tendency of the disease to become septicemic just before death.
That these statements are founded upon a firm basis, is by no means obvious. The results obtained by different observers would appear to ary considerably. WILM was able to find plague bacilli in the blood stream of cases of all varieties of the disease some considerable time before death.
The results obtained by other observers, however, have been more or less negative. From these cases which have just been described, it is seen that the diagnosis of plaque was made from a microscopical examination of the blood during the initial stages of the disorder, and further the method employed gave extremely reliable results.
This is in direct opposition to the views held by the majority of plague workers of the present day. Their views I have only just mentioned.
The presence of the B. pestis in the blood of plague patients during the early stages of the disease, appears to me to be of the greatest importance. Further the thick blood film method of Ross applied to plague hæmatology, is a most useful addition to the methods of diagnosis of cases of plague. Dr. BELL has told me that these bacilli have been found in the blood during the initial stages of all types of the disease, namely, the bubonic, pneumonic and septicemic.
In the septicemic types of the disease (and as already mentioned, the existence. of this form of plague is almost denied by some), the demonstration of the causal agent in the blood excites no surprise, but when we find that similar results are attainable in the other varieties of the disease, our ideas in regard to the pathology of plague must necessarily change. Everr granted that the method is not abso- lutely reliable (and no method in bacteriology is infallible), the finding again and again of plague bacilli in the peripheral blood stream during the early stages of the disease, is a new fact, and one which alters the present day conceptions of plague. That the micro-organisms found in the thick blood films were plague bacilli, there can be no doubt.
At the commencement of Dr. BELL's examinations of the blood of suspicious cases of plague, many of the slides were shown to me, and I must confess, that I was sceptical as to the reliance, which could be placed on the method as one for